Before you spend a lot of money on new tiles, look into your garage. Do you see a gallon of chlorine bleach and a gallon of white vinegar? Great! Now go back to your bathroom and check out if you have a spray bathroom cleaner. If you ran out you can use basically any ultra mild abrasive cleaner.
Don’t think this one is going to be easy. After all, the mildew stains took months to develop and it will take a couple of days to completely remove.
Before you start using the bleach and other cool stuff you have to spray the tiles with a cleaner and thoroughly scrub with a short bristle brush to remove not only mildew but also soap leftovers etc. Most probably the surface of your tiles will shine like a mirror. On the other hand, your grout will most probably will still be gray (and ugly).
Now it’s time for the fun part. Saturate paper towels with chlorine bleach and put these in contact with the grout. Check out your paper towels every few hours making sure they are wet. Depending on how stained your grout is this may take up to 3 or 4 days.
With that said, now comes the warning part: Bleach can be dangerous! I really meant it. Of course, you will smell this chemical’s fumes but that shouldn’t worry you as brief encounters shouldn’t cause harm. On the other hand, bleach should be used with caution as inhaling its fumes can cause irritation of the airway passages. So, be careful and if you have any questions do not hesitate to ask.